Linux Host Configuration

Linux

Audience

Public

Product

FlashBlade

FlashArray

Technology Integrations

Linux

Source Type

Documentation

1. Before you begin, make sure that you are following the Linux Recommended Settings before proceeding.

Note: If multiple interfaces exist on the same subnet in RHEL, your iSCSI initiator may fail to connect to your Everpure target. In this case, you need to set sysctl's net.ipv4.conf.all.arp_ignore value to 1, to force each interface to only answer ARP requests for its own addresses. Please see RHEL KB for Issue Detail and Resolution Steps (requires Red Hat Customer Portal login).

2. Install the


            iscsi-initiator-utils

package and device-mapper-multipath as root user.

$ sudo su
# yum install iscsi-initiator-utils
yum install device-mapper-multipath

3. Start the iscsi service and enable it to start when the system boots.

For RHEL9 and RHEL8:

# systemctl enable iscsid
# systemctl start iscsi

Note: The host’s iSCSI qualified name (IQN) is automatically generated upon startup, and it can be found in /etc/iscsi/initiatorname.iscsi. Add the IQN value to the host defined in Purity.

To discover the FlashArray's IQN, run the following command.

# iscsiadm -m discovery -t st -p [Flash Array domain name or IP address] -o new

Note: If there are multiple NICs that service iSCSI traffic, one IQN might be listed multiple times on different IP addresses. This is because there are multiple possible paths from a host to a FlashArray.

You can also log into the FlashArray GUI and gather the IQN and IP addresses.

Settings > Network > Ethernet

Health > Connections > Ethernet Port

Repeat the following step for each IP address, or path, you use.

# iscsiadm --mode node --targetname [IQN on the Flash Array] --portal [IP address:port] --login

The following example illustrates how to perform this step with sample IQN and portal values.

# iscsiadm --mode node --targetname iqn.2010-06.com.purestorage:flasharray.5d4c44fed1159599 --portal 10.21.229.100:3260 --login
# iscsiadm --mode node --targetname iqn.2010-06.com.purestorage:flasharray.5d4c44fed1159599 --portal 10.21.229.101:3260 --login

iSCSI devices mapped to the host should now appear in the Linux SCSI device table in /dev/sd*. You should also see a message, such as the following example, in the Linux /var/log/messages log.

#  grep "Attached SCSI" /var/log/messages                                                  
Sep 11 15:12:41 localhost.localdomain kernel: sd 33:0:0:1: [sde] Attached SCSI disk
Sep 11 15:12:41 localhost.localdomain kernel: sd 33:0:0:2: [sdf] Attached SCSI disk
Sep 11 15:22:19 localhost.localdomain kernel: sd 34:0:0:1: [sdg] Attached SCSI disk
Sep 11 15:22:19 localhost.localdomain kernel: sd 34:0:0:2: [sdh] Attached SCSI disk

For RHEL7:

# systemctl start iscsid.socket
# systemctl enable iscsi

The iscsid.socket would start iscsid.service if stopped. At this stage, the status of the iscsi service might be seen as active. After the discovery command, the service should start.

For RHEL6:

# service iscsi start
# chkconfig iscsi on

4. Before you set up DM Multipath on your system, ensure that your system is up to date and that it includes the device-mapper-multipath package.

# yum install device-mapper-multipath device-mapper-multipath-libs

5. Enable the default multipath configuration file, and then start the multipath daemon.

# mpathconf --enable --with_multipathd y

6. Edit the /etc/multipath.conf file with the following recommended multipath config.

# vi /etc/multipath.conf

See the Everpure RHEL documentation for /etc/multipath.conf attribute descriptions.

# This is a basic configuration file with some examples, for device mapper
# multipath.

## Use user friendly names, instead of using WWIDs as names.
defaults {
        user_friendly_names yes
        find_multipaths yes
}

multipaths {
        multipath {
                wwid                    3624a9370ae191d6c184648460001141e
                alias                   asm-data1
                uid                     grid
                gid                     asmadmin
                mode                    660
        }
        multipath {
                wwid                    3624a9370ae191d6c184648460001141f
                alias                   asm-data2
                uid                     grid
                gid                     asmadmin
                mode                    660
        }
}

blacklist {
}

7. Restart the multipath service for the multipath.conf changes to take effect.

# service multipathd restart

8. Add the iSCSI devices to multipathing with the multipath -a command, shown in the following example.

# multipath -a 3624a937081f096d1c1642a690269dad0
wwid '3624a937081f096d1c1642a690269dad0' added
# multipath -a 3624a937081f096d1c1642a690269dad1
wwid '3624a937081f096d1c1642a690269dad1' added

9. Verify that multipathing is now managed for the selected devices. Successful verification should produce results as shown in the following example.

# multipath -ll
asm-data1 (3624a937081f096d1c1642a690269dad0) dm-3 PURE,FlashArray
size=4.0G features='0' hwhandler='1 alua' wp=rw
`-+- policy='service-time 0' prio=50 status=active
  |- 33:0:0:1 sde 8:64  active ready running
  `- 34:0:0:1 sdg 8:96  active ready running
asm-data2 (3624a937081f096d1c1642a690269dad1) dm-4 PURE,FlashArray
size=4.0G features='0' hwhandler='1 alua' wp=rw
`-+- policy='service-time 0' prio=50 status=active
  |- 33:0:0:2 sdf 8:80  active ready running
  `- 34:0:0:2 sdh 8:112 active ready running